The invention pertains to apparatus and methods for handling the flow of fluids such as air. More particularly, the invention relates to the use of air turning vanes with a porous surface where air is discharged from a plenum into, e.g., an internal volume. Even more particularly, the invention relates in some embodiments to the use of air turning vanes on a discharge plenum wall of an environmentally controlled cabinet, such as on an oven""s discharge plenum wall having discharge parts.
In many circumstances, for example in some industrial applications, a porous wall is provided where a fluid such as air is flowing in a first direction on a first side of the wall and the fluid passes through the porous wall and exits the other side of the wall in a second direction which may be different from the first direction. For example, many types of environmental chamber units are known in which a fluid such as air is circulated into and out of an internal volume in order to treat components that are placed within the internal volume. For example, in the case of a convection oven, it has been known for the convection oven to include an outer cabinet surrounding an enclosure defining an internal volume area formed by a lower wall, and upper wall, and four side walls. In such convection ovens, it is common for one side wall to be a porous air inlet wall and another side wall to be a porous air return wall. The inlet wall may have supply plenum and a plurality of air supply ports, such as evenly spaced round holes, that supply air to the internal volume. The air then flows through the internal volume and returns via the porous return wall to an air return plenum located on the other side of the wall. Often, this air return plenum has a constant vertical cross-sectional area and extends all or substantially all the height and width of the side wall. Air is drawn vertically down through the air return plenum into a plenum, such as for example a substantially horizontal lower plenum, which includes some type of fan or blower element that pressurizes the air towards a discharge plenum.
The discharge plenum is typically a vertical plenum on the air inlet wall opposite to the air return side wall, and extends upwardly outside of the air inlet wall. In some instances, the air discharge plenum will have a constant cross-section similar to the air return plenum. It has been found that in these situations that the air will discharge out of the discharge plenum openings at a some what upward angle. That is, the air does not exit through the discharge plenum openings completely horizontally, but rather exits at a discharge angle, which may, for example, be 45xc2x0 upwards.
Having an upward angle component to the discharge direction is disadvantageous because a greater amount of heated discharge air tends to be forced into the upward region of the interior volume. At the same time, the heated discharge air tends not to flow past the lower portions of the interior volumes. This provides a significant disadvantage because items to be heated that are placed in the upper part of the discharge volume tend to receive a greater heat load than those in the lower part of the internal volume. Thus, it is difficult to provide an even heat transfer to parts located in different vertical areas of the interior volume.
One approach to solving this problem has been the use of a substantially horizontal porous baffle located at one or more heights inside the discharge plenum, for example, approximately midway up the height of the discharge plenum. Such a horizontal internal baffle will cause the row of discharge jets located just below the baffle to emit a particularly strong discharge jet. The strong discharge jet can be located to help even out the internal temperature profile of the oven to some extent. However, the use of a porous baffle still does not provide a completely even temperature profile and does not completely overcome the above problems.
Another partial solution has been to provide the plenum with a gradually decreasing cross-section along its height. Near the lower part of the plenum, the plenum has a relatively large cross section. The plenum wall opposite the plenum discharge wall is angled so that the interior cross sectional area of the plenum is relatively small near the top of the plenum.
With a constant cross sectional discharge plenum area, the discharge jet angle near the top is more than the discharge jet angle at the bottom. That is, for a vertical plenum with upwardly flowing air, the discharge jets are more horizontal at the top than the bottom. However, with either constant or decreasing plenum cross-sections, the jet still are emitted at an angle, and there is a tendency for the lower portion of the internal volume to be cooler because a heated jet is not directed horizontally towards that area.
Yet another partial solution to the problem of vertical components to the discharge angle has been to shrink the size and/or number of the holes so that the plenum wall has a relatively smaller total open area for discharge. This provides a larger more horizontal discharge angle. However, it has the disadvantage that the volumetric flow rate is reduced because of a high pressure drop across the supply plenum wall.
Accordingly, there is a need in the art for a method and apparatus for directing fluid discharge from porous walls so that the fluid may be directed in a particular direction. There is an even more specific need in the art for methods and apparatuses for directing air that is exiting a porous plenum wall so that it can be directed in a predetermined direction, for example substantially perpendicular to the plenum wall from which it is exiting. Moreover, there is a need in the art for a method and apparatus that is relatively easy and inexpensive to manufacture and install.
The above disadvantages are overcome at least to a great extent by embodiments of the present invention, which provides in some embodiments a method and apparatus for directing a fluid such as air which is exiting from a porous plenum wall.
In one aspect, the invention provides an apparatus for use with a porous wall having a first side and a second side, with a fluid flowing on the first side generally in a first direction. The apparatus comprises: at least one vane member located proximate to the second side of the discharge wall and having a profile that directs the discharge air from the second side in a second direction.
In another aspect, the invention provides an air handling apparatus having a plenum containing fluid moving in a first direction; a porous plenum wall permitting said flow from the plenum through the plenum wall to exit the plenum via an exit side; and at least one vane member located on said exit side of the plenum wall that directs exiting fluid flow in a predetermined second direction.
In another aspect, the invention provides an apparatus for use with a porous wall having a first side and a second side, with a fluid flowing on the first side generally in a first direction, the apparatus comprising: means located proximate the second side of the discharge wall or directing the discharge air from the second side in a second direction; and means for supporting said directing means.
In another aspect the invention provides a method for use with a porous wall having a first side and a second side, including the steps of: directing a fluid on the first side generally in a first direction; and directing discharge air from the second side in a second direction using at least one vane member.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings.
The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.